CCENUROSIS (GID, STURDY, TURN-SICK). 467 



CCENUROSIS (GID, STURDY, TURN-SICK). 



CcBnurosis is a disease due to invasion of the animal body by em- 

 bryos of larv.ie of the Ttenin c< munis of dogs and wolves. These embryos 

 only develop freely in the Ijrain substance {Cirmirus ceirliralis) and 

 medulla oblongata. The hosts of the larvae include the calf, sheep, goat, 

 roedeer, reindeer and horse. 



The disease was formerly erroneously called " turn-sick," for the 

 turning is only a manifestation, and even a tardy manifestation, of 

 the disease, while in addition it is not invariably present. 



Coenurosis principally attacks lambs of from three to six months, 

 although it occurs up to eighteen months, and sometimes even two 

 years. It is exceptional, however, in adults. Similarly in the bovine 

 species it usually affects young animals up to the fourth or fifth year. 



Coenurosis with diffuse parasitic encephalitis often remains unrecog- 

 nised, the animals being regarded as affected with epizootic meningitis 

 of unknown cause or septic intoxication, and when they die the owners 

 are ignorant as to the cause of death. The stage corresponding to turn- 

 sick, which is an advanced phase of the disease, is only seen in animals 

 which have been infested to a slight extent, and in which three or four 

 parasities only, sometimes only one, have attained the brain and de- 

 veloped there. Such cases exhibit all the classic symptoms of turn- 

 sick, viz., turning movements, heaviness, vertigo, etc. 



Causation. Coenurosis is due solely to one cause, viz., the inges- 

 tion of eggs or embryos in feeding or drinking. 



The Tonna c(v>iurus lives in the dog, and fertilised segments are 

 passed with the fseces in yards, pastures and fields, and on the margins 

 of roads, ditches and ponds. Amongst damp grass or in water the eggs, 

 which contain more or less well-developed embryos, may retain their 

 vitality for several weeks, and when swallowed the embryos are set 

 at liberty in the intestine. 



The six-hooked embryos perforate the walls of the intestine, pass 

 into the blood stream or chyle ducts, and from these points are carried 

 in all directions. Tliose which gain the nervous centres, the brain or 

 spinal cord, continue to develop; the others, dispersed through diffe- 

 rent tissues, degenerate and disappear. 



Experimental infection with these parasites shows that the brain is 

 invaded after about a week's time. From the twentieth day the presence 

 of embryos can easily be detected in the superficial layers of the convo- 

 lutions. They make their way through the grey substance, leaving 

 behind them greenish-yellow sinuous tracts with caseous contents. 



The cyst or finn undergoing development can be found at the end of 

 one of these tracts in the form of a little transparent bladder, of a size 



H H 2 



